About the Book
Table of Contents
Part V: Is Man An Animal?
The Ubiquity of Man
Comparative Defenselessness of
MAN IS surely
the most defenseless of all creatures, unless armed artificially.
(93) He appears
to have no dependable instincts for self-protection. (94) What natural defenses
he can muster from within himself are puny compared with those
of animals. And there is no evidence that early man was very
different from ourselves, so that we cannot blame this deficiency
altogether on a cultural heritage which tends to supply us with
substitute defenses. The strength of animals relative to human
strength is tremendous. A chimpanzee, for instance, has something
like three to five times the strength of man, though considerably
less weight (120 lbs.). (95) The fact of man's helplessness in terms of self-defense
has been remarked upon by many writers, not a few of whom have
seen in it, quite rightly, one of the reasons for his ability
to exercise dominion over the rest of Nature. For in lieu of
natural equipment he has been granted superior intelligence and
learned to arm himself accordingly.
Years ago Sir William Dawson made
this statement: (96)
It is, in animals below man,
a law that the bodily frame is provided with all necessary means
of defense and attack, and with all necessary protection against
external influences and assailants.
In a very few cases, we have a
partial exception to this. A hermit-crab, for instance, has the
hinder part of its body unprotected; and has, instead of armor,
the instinct of using the cast-off shells of mollusks; yet even
this animal has the usual strong claws of a crustacean for defense
in front. There are only a very few animals in which instinct
thus takes the place of physical
93. It is possible that honours in this respect
may have to go to the koala bear which, I have read, is completely
94. Animals appear to know when to stand and fight, and when
it is wiser not to do so. This is particularly true of birds,
as noted by Alexander F. Skutch, "The Parental Devotion
of Birds," Scientific Monthly, April, 1946,
95. Noted by R. A. Gardner, Science, vol.165, 1969, p.664.
96. Dawson, Sir William, The Story of Earth and Man, Hodder
and Stoughton, London,1903, p.365.
contrivances for defense or attack, and
in these we find merely the usual unvarying instincts of the
animal. But in man, that which is the rare exception in all other
animals becomes the rule. He has no means of escape from danger
compared with those enjoyed by other animals, no defensive armor,
no effective weapons for attacking other animals.
These disabilities should make
him the most helpless of creatures, especially when taken with
his slow growth and long immaturity. His safety and his dominion
over other animals are secured by entirely new means, constituting
a new departure in creation. Contrivance and inventive
power, enabling him to utilize the objects and forces of Nature,
replace in him the physical powers bestowed on other animals.
Obviously, the structure of the
human being is related to this, and so related to it as to place
man in a different category altogether from any other animal.
from antiquity, from the study of fossil man and his cultural
remains, indicates that man has always had to depend upon his
intellect rather than his physical strength or natural defensive
weapons. If man had not fallen, it is my belief that he would
not have had to defend himself against other animals at all,
but would have achieved dominion over them by a kind of power
akin to moral force. Even yet there are among us individuals
who seem to have retained something of this power over animals.
It would be an interesting question for debate to ask whether
many of the defensive instincts of animals would have been necessary
if sin had not entered into God's creation, and therefore whether
they were conferred upon them by God as soon as man's sin began
to disrupt the natural order. Fabre, with the true insight of
a devout naturalist, recognized animal instinctual behaviour
as "inspired activity." (97)
But returning to early man, a keen
student of civilization, Vere Gordon Childe, wrote:(98)
Man is now, and was apparently
even at his first appearance in the Pleistocene, inadequately
adapted for survival in any particular environment. His bodily
equipment for coping with any set of conditions is inferior to
that of most animals. He has not, and probably never had, a furry
coat like the polar bears for keeping in the body's heat under
cold conditions. His body is not particularly well adapted for
escape, for self-defense, or hunting.
He is not, for instance, exceptionally
fleet of foot, and would be left behind in any race with a hare
or an ostrich. He has no protective coloring like the tiger or
the snow leopard, nor bodily armor like the tortoise or the crab.
He has no wings to offer escape and give him an advantage in
spying out and pouncing upon prey. He lacks the beak and talons
of the hawk, and its
97. Fabre Henri: quoted by W. R. Thompson
in a Convocation Address: "The Work of J. Henri Fabre",
in Canadian Entomology, vol.96, nos.1 and 2, 1964, p.70.
pg.2 of 16
98. Childe, Vere Gordon, Man Makes Himself, Thinkers Library,
Watts, London, 1948, p.23.
keenness of vision. For catching his
prey and defending himself, his muscular strength, teeth and
nails are incomparably inferior. . . .
As Kipling said,
man is indeed "a poor naked frog."
And yet man has a vast superiority, for
all his weakness and in spite of the Fall. He did not entirely
lose in Eden the power to obey the command to have dominion over
the earth. The processes of civilization are really only exhibitions
of this ability expressed in terms of fallen man. During World
War II, C. E. M. Joad, a man who thought deeply about the events
of his day, wrote a little pamphlet entitled For Civilization.
His opening paragraph reads as follows: (99)
Wherein are to be found the
distinctive characteristics of our species? In what, that is
to say, do men differ from and excel the beasts? In swiftness
or ferocity? The deer and the lion leave us far behind. In size
and strength we must give way to the elephant and the whale;
sheep are more gentle, nightingales more melodious, tortoises
longer-lived, bees more cooperative, beavers more diligent. The
ants run a totalitarian State much better than any Fascist.
The truth is that our bodies are
feeble and ill-adapted to survival; they are the prey to innumerable
diseases, their enormous complexity means that things can go
wrong in a vast number of ways, while so poorly are they equipped
against the vagaries of the climate that it is only by clothing
ourselves in the skins of other animals that we can survive.
All these things
are true, but not the whole truth, and Dawson, Childe, and Joad
from their different points of view would at once acknowledge
this. It is true that man is not supplied with natural defenses
against potential enemies, but he does have a brain and hands
which allow him to design vastly superior weapons for himself.
It is true that he is naked, but these same hands and brain allow
him to devise clothing which gives him the ability to live where
other animals cannot live, except under his protection. He may
indeed be slow to move, yet these same hands and brain have made
him more mobile and faster than any other creature. And though
he may apparently be ill-protected against the vagaries of climate,
he is nevertheless, physiologically speaking, quite uniquely
equipped to maintain his deep body temperature within remarkably
narrow limits over an extraordinary wide range of external conditions
of temperature, pressure, and humidity. And as we shall see,
in his diet he is further exceptionally fitted to live in any
part of the world.
Many years ago Alexander Macalister,
professor of anatomy in the University of Cambridge, wrote a
paper entitled "Man, Physiologically Considered," in
which he was careful to note that
99. Joad, C. E. M., For Civilization, Macmillan
War Pamphlets, London, 1940, p.3.
there are many features
of man's anatomy and physiology which contribute to the use he
has made of his superior brain: (100)
While it is thus power of mind,
not power of body, which gives to man his supremacy, yet, in
all respects, man's bodily organization is fitted to enable
him to use to the best advantage his mental endowments.
If he conceives in his mind the
plan of making a weapon, his prehensile hand with its sensitive
skin and its independently moving and opposable thumb can fabricate
it. His sinuous backbone and completely extensile lower limbs
enable him to stand upright with perfect stability, with an ease
and perfection competent to no other animal; and thus his forelimbs,
relieved from all necessity to act as organs of progression,
are perfectly disengaged for work. . . .
His very weakness
has in the providence of God served to enhance man's chief glory,
his power to think things through. But his superior mental abilities
had to be supported adequately to find expression through the
other members of his body, and his body needed to be organized
in a number of ways uniquely to make this possible. It was God's
intention that he should fill the earth and govern it, and there
is little doubt that when this command was given, the climatic
conditions on earth were not fundamentally different from what
they are today in that while there were zones where the temperature
was moderate and laid little stress on the body, there were other
zones where man was going to experience considerable heat stress
or cold stress. It may be perfectly true that if Paradise had
not been lost, the world's climate would have been uniformly
temperate, though this would involve tremendous geophysical modifications.
But undoubtedly God knew what man would do and that he would
face in the end the task of filling a world in which climatic
extremes would exist as they do now. He must therefore have been
designed, to begin with, with the capability of making the necessary
physiological adjustments in order to occupy these challenging
zones. No other animal was designed, it seems, for such ubiquitousness.
Next, let us just consider the
nature of territoriality of animals other than man; then, the
significance of man's uniformity of physical type in spite of
his wide dispersal and often long isolation; and finally, all
too briefly, the complex mechanisms by which man maintains his
deep body temperature at the optimum level to allow the exercise
of his full potential as a thinking creature within an exceptional
range of external conditions. This study will serve to
100. Macalister, Alexander, Man Physiologically
Considered, vol.7, no.39 in Present Day Tracts, Religious
Tract Society, London, 1886, pp.6, 7.
pg.4 of 16
demonstrate that this
mechanism in man is in certain fundamental respects quite different
from the mechanism which serves somewhat the same purpose in
animals, and this will underscore at the same time the fact that
it is easy for the in-expert to suppose that because the mechanisms
look alike they are in fact the same.
Man the Free‹roaming
the extent of animal territories. Every increase in our knowledge
of this subject only tends to confirm that all animals have limited
territories, which they mark out rather specifically. Often more
than one species will occupy a single area, but each species
marks out its territorial boundaries in defiance of other members
of its own species. In the case of social animals, the
territory owned by the individual may be quite small. Birds,
especially sea birds, may claim only space sufficient to land
upon and lay their eggs. But other animals, like some of the
large cats, may dominate territories covering a number of square
miles. Just as an illustration of the kind of spread involved,
the weasel may claim from two to nine acres, a male stoat up
to eighty-five acres, martens about one square mile, a waterbuck
anywhere from forty to five-hundred acres, some bears, ten square
miles or more, and a pride of fifteen lions, thirty or more square
miles. (10l) The
territory of animals which migrate should not strictly include
their corridors of migration which they merely pass through,
but must be limited to their range of wintering or summering.
The primates nearest in form to man claim territorial rights
over far less territory, the proportion working out to about
two and one-half chimpanzees per square mile, for example. (102) The Sifaka monkeys in
Madagascar occupy about three acres each.
Social animals that live in colonies
seem to crowd their environment, but apparently, except under
stress, they do not actually compete severely for the food supply.
Herds of animals may live with herds of another species, serving
as sentinels for one another but not competing for the available
food because their diets are different. I think it is amusing
that evolutionists who believe that Nature has advanced itself
by the very fact of competition are also able to turn around
and show that evolution has often had the reverse effect, i.e.,
limiting competition. So we have a situation in which competition
leads to evolution upwards while evolution tends towards the
elimination of competition. Thus a magnificent volume, The
101 The Living World of Animals, edited
by L. Harrison Matthews, Readers Digest Publication, London,
1970, pp.56, 58, 59, 101, 106.
102. Ibid.: Chimpanzees, p.198; Sifaka monkeys. p.215.
Of Animals, under the editorship of L. H. Matthews and others,
has this enlightening paragraph: (103)
This concentration of animals
(in Africa) does not lead to the severe competition between species
for food that might be expected, because each has his own preferences
even when several different species graze upon the same plant.
Red Oat grass, for instance, is eaten by the zebra, the wildebeest,
and the topi, but each feeds upon it at a different stage of
the plant's growth. This limited competition, the result
of evolution [my emphasis], has permitted a great variety
of animals to fit into the environment; every species has its
niche, from the smallest insect to the elephant.
Not only are
animal territories rather precisely defined, but the geographic
distribution of species tends to be equally well defined, except
where man has interfered and taken domesticated animals with
him. Of the primates, the gorilla is confined to a small tract
of West Africa about the size of France. The chimpanzee, although
ranging over a larger district of Equatorial Africa, still does
not extend beyond the region limited by the parallels 12 degrees
north and south latitudes, and in this belt is only found between
the sea coast on the west and the meridian of Lake Tanganyika
on the east. The orangutan is limited to the islands of Sumatra
and Borneo. (l04)
Washburn and Lancaster, in a paper
on the evolution of hunting, remark upon the difference between
the territory occupied by men who hunt as opposed to animals
which hunt: (105)
Social groups of non-human primates
occupy exceedingly small areas, and the vast majority of animals
probably spend their entire lives within less than 4 or 5 square
miles. Even though they have excellent vision and can see for
many miles, especially from the tops of trees, they make no effort
to explore more than a tiny fraction of the area they see.
Even for gorillas the range is
only about 15 square miles, and it is of the same order of magnitude
for savanna baboons; they refuse to be driven beyond the end
of their range and double back. The known area is a psychological
reality, clear in the minds of the animals. Only a small part
of even this limited range is used, and exploration is confined
to the canopy, lower branches, and bushes, or ground, depending
on the biology of the particular species. . . .
In marked contrast, human hunters
are familiar with very large areas. In (one) area studied . .
. eleven water holes and several hundred square miles supported
a smaller number of Bushmen than the number of baboons supported
by a single water hole and a few square miles in the Amboseli
Reserve in Kenya. The most minor hunting expedition covers an
103 Ibid., p.96.
pg.6 of 16
104. Macalister, Alexander, Man Physiologically Considered,
vol.7, no.39, Present Day Tracts, Religious Tract Society
of London, 1886, p.5.
105. Washburn, S. L., and Lancaster, C. S., "The Evolution
of Hunting," in Human Evolution, edited by N. Korn
and F. Thompson, Holt, Rinehart & Winston, New York, 1967,
larger than most non-human primates would
cover in a lifetime. Interest in a large area is human.
It is not unusual
for a single Eskimo family to occupy for hunting purposes a territory
stretching for 200 to 300 miles. Moreover, unlike any other species,
man seems by nature a wanderer and an explorer, to whom no part
of the globe does not have an appeal in one way or another. Man
is truly ubiquitous.
Comparative Absence of Physical
For all his
ubiquity man has not, even in those earlier periods of history
in which population was thin and tribes were often isolated for
centuries, developed varieties of the species Homo sapiens
to anything like the extent that animals have. It is true
that in one area of the world, Africa, we do have Pygmies whose
average height is perhaps four feet six inches, and Nilotic Negroes
whose average height may be around seven feet, but in terms of
body mass the difference between the Nilotic Negroes and the
Congo Pygmy is far less than, for example, the difference between
the St. Bernard and the Chihuahua. Moreover, this apparent limitation
in terms of variability within the family of man has made it
possible for all races to interbreed freely. In the case of the
St. Bernard and the Chihuahua, for example, interbreeding is
not successful for physical reasons unless artificial means are
used. And if the mother is the Chihuahua, she apparently cannot
bear her pup sired by a St. Bernard because of its size at full
Within the animal kingdom other
factors may result in psychological blocks to successful mating
-- the time of heat of varieties of a single species too-long
separated may not be in register; sometimes the block is apparently
due to unacceptable body odour caused by a difference in diet.
The inflexibility of the period of heat among species, an inflexibility
which is governed by their need to bear their young at an appropriate
time in the year, is said by some authorities to be responsible
for the extinction of at least some species in early Pleistocene
times when it is held that great climatic changes were taking
Experience shows, by contrast,
that none of these barriers exist between members of the human
species, though they may be brought together from the ends of
the world for the first time in human history. Mankind as a species
has not a restricted "season of
106. Slaughter, W. H., "Animal Ranges
as a Clue to Late-Pleistocene Extinctions," in Pleistocene
Extinctions, vol.6 of the Proceedings of the 7th Congress
of the International Association for Quaternary Research, edited
by P. S. Martin and H. E. Wright, Yale University Press, 1967, p.155.
heat," such as characterizes
all other species. And this fact has tremendous importance, as
we shall see in the next chapter. The potential for interbreeding
successfully seems to me to indicate that, unlike other animals,
man was uniquely designed from the beginning to be able to go
anywhere in the world without becoming a genetic isolate.
Although I cannot find myself in
agreement with Teilhard de Chardin, he is certainly correct in
underscoring the importance of this fact for man: (107)
By climatic and geographical
influences, varieties and races (of animals) come into existence.
Somatically speaking, the fanning out (of man) is present
continually in formation and perfectly recognizable. Yet the
remarkable thing is that its divergent branches no longer succeed
Under conditions of distribution
which in any other initial phylum would long ago have led to
the breakup into different species, the human vertical as it
spreads out remains entire, like a gigantic leaf whose veins,
how ever distinct, remain always joined in a common tissue. With
man we find independent (interfertility) on every level. . .
Zoologically speaking, mankind
offers us the unique spectacle of a species capable of achieving
something in which all previous species had failed. It has succeeded,
not only in becoming cosmopolitan, but in stretching a single
organized membrane over the earth without breaking it.
It is clear,
then, in a way which has never been demonstrated for animals,
that every variety of man is "made of one" (Acts 17:26,
where the word "blood" is probably not part of the
original text). And this true unity of such a far-flung race
guarantees that throughout history One Man could always be recognized
as a true representative of all men, without exception.
Another notable circumstance with
respect to animal populations is the interesting fact that according
to our present understanding, animal species remain remarkably
stable in terms of the number of individuals constituting each
particular species. Were it not so, of course, their territories
would have to increase or they would have to become progressively
more crowded. Darwin saw that all organisms possess the potentiality
for increase, a potentiality not merely for arithmetical multiplication
but geometric. It was this belief that led him to assume that
Malthus' essay on human population growth must also apply to
animals. He therefore postulated an unending
107. Teilhard de Chardin, Pierre, The Phenomenon
of Man, Collins, London, 1955, p.241. A more "orthodox"
authority, G. G. Simpson, has remarked upon the same circumstance:
"Regardless of the diversity of races, it is obvious that
all men resemble one another much more than any of them differ
from each other. They all share the basic quality, anatomical,
physiological and psychological, that make us human, Homo
sapiens, and no other species that is or ever was" (Biology
and Man, Harcourt, Brace & World, New York, 1969, p.87).
pg.8 of 16
struggle to survive,
with the triumph of the fittest. We know now that this was an
entirely erroneous extrapolation from human to animal population
growth. Sir Julian Huxley himself underscored the fact that for
various reasons this population growth does not materialize,
and so he observed, "In spite of the tendency to progressive
increase, the numbers of a given species actually remain more
or less constant." Subsequently, he wrote: (108)
With our much greater knowledge
of ecology, we know today that many species undergo cyclical
and often remarkably regular fluctuations, frequently of very
large extent in their numbers.
At this point,
he referred to the work of Charles Elton, and although I do not
have the work he refers to, I do have a similar work by that
author in which he underscored this interesting finding, and
after giving some specific illustrations, concluded: (109)
All this goes to support the
idea that there is some important principle involved in the stability
of the total number of species in an animal community.
Elton was speaking in this case not of the
number of individuals in a species but the number of species
in a given area. This is a fact which has been recognized for
a long while: namely, that when any particular species dies out,
some other species will move in to fill the ecological niche
which has thus become vacant. But they do not over-populate it.
So the web of life is preserved intact, and the total number
of animals as a consequence remains remarkably constant. The
pattern of human population growth is quite otherwise. Were it
not so, man would never finally "fill the earth." But
did those constraints against anima/ population growth
not exist, it could very well be that the animals, rather than
man, would have usurped his dominion long before this.
In the meantime, evidence has recently
come to light that, again, unlike human beings, animals are somehow
able to control their own numbers, not by killing off unwanted
children as it were, but by producing fewer offspring. This has
become apparent, for example of the elephant population in the
Murchison Falls area of Western Uganda in Africa. (1l0) Where one section of
this particular population has had its territory reduced by the
extension of farming,
108. Huxley, Sir Julian, Evolution:
the Modern Synthesis, Harper, New York, 1942, p.15.
109 Elton, Charles, The Ecology of Animals, Methuen, London,
1950, p.20. See also his "Animal Numbers and Adaptation"
in Evolution: Essays on Aaspects of evolutionary Biology,
edited by Sir Gavin de Beer, Oxford University Press, 1938,
110. Animal population stability: Robert Ardrey, in a series
of two articles on the subject in The Globe and Mail, Toronto,
September 30 and October 1, 1971.
the elephant population
has somehow diminished by a change in the birth rate.
The normal spacing for calves is four years; in this potentially
over-crowded area it has risen to nine years. No one knows the
mechanics of this, though it has recently been recognized that
the same thing may happen in other parts of the world. In an
English woodland, if the number of great-tits doubles, in the
next season the egg clutch size will be reduced by two. In an
Iowa marshland, if muskrat numbers rise too high, then the mother
muskrat produces fewer embryos or re-absorbs them.
Man the Omnivorous
which contributes to man's unique ubiquity is his willingness
and ability to accept a vegetarian or meat diet with equal ease.
There are millions of people who for centuries have been to all
intents and purposes vegetarian, such as those in the Far East
who depend upon cereals (rice, etc.). By contrast, there have
been branches of the human race, such as the Eskimo people, who
were not completely but almost entirely meat eaters. At certain
seasons of the year they probably had some fruits in the form
of wild berries. The human body, therefore, can be nourished
equally well by either form of diet.
By contrast, as Loren C. Eiseley
says, "All of the existing great apes are essentially vegetarian,
and indeed the arboreal bracchiators have no other consistent
source of food." (111) Whether these creatures could successfully adopt
a carnivorous diet without completely changing their character,
or at least becoming no longer interfertile with members of their
own species who remain vegetarian, it is difficult to say. It
is known that in at least one branch of the primates, a number
of animals have changed their diet from a herbivorous to a carnivorous
one due to man's disturbance of their natural environment. Eugene
Marais pointed out that up until about 1860 the wild baboons
in Africa fed on insects and roots. (112) In a manner of speaking, they were therefore already
omnivorous, though insects as part of a diet do not usually qualify
the eater as a carnivore. But the drying up of the continent
due to man's bad farming management, forced these animals to
look for liquid to drink from new sources, and they started killing
goats just to suck the milk from their udders. In time they began
attacking all kinds of domestic animals and eating them for food.
111. Eiseley, Loren C., "Fossil Man and
Human Evolution," in Current Anthropology, edited
by W. L. Thomas, University of Chicago Press, 1956 , p.73.
pg.10 of 16
112 Marais, Eugene, My Friends, the Baboons, Methuen,
New York, 1939, p.1.
This is an exceptional circumstance, not a natural
one. And the fact remains that virtually no other animal bearing
some similarity to man is equally capable of living on either
a vegetarian or a meat diet. This is of great importance to man,
for there are areas of the world where vegetables are simply
not available (for example, desert areas and the high Arctic)
unless they are imported. The settlement by man of such areas
would therefore have been altogether impossible unless he had
been omnivorous by nature. Man's constitution is therefore such
that in this also he is uniquely equipped to fill the earth and
subdue it in a way that no other creature is.
Man the Supreme Homeotherm
We come, then, to one further aspect
of human constitution which is easily overlooked but is of equally
profound significance for man in the light of his original commission.
This has to do with the means by which he maintains his body
animals, whether cold-blooded or warm-blooded, must have some
temperature regulation in order to sustain life, there are
ascending degrees of regulation as we move up the scale of complexity
in animal form. The cold-blooded animals are not strictly cold-blooded.
They are so constituted that within certain limits their body
temperature floats with the environmental conditions, and the
amount of energy they have fluctuates accordingly. They are sluggish
and virtually defenseless when the environmental temperature
falls below a certain level, because energy is derived in the
animal body by the "burning" of food stuffs and this
burning process becomes very inefficient at low temperatures.
Obviously, such creatures must be able to prevent a fall below
a certain point, otherwise they would lack energy even for digestion
and other vital processes. They can, however, sustain a fall
in deep body temperature far below that of warm-blooded animals.
This is an advantage to them in terms of survival where they
are not in danger of attack from other animals, but it severely
limits their potential for accomplishment. The next level seems
to be found in those animals which, although they are able to
maintain their body temperature quite close to that of man, nevertheless
have the ability to allow their temperature to fall everywhere
in the body except in certain vital organs. There are animals
which can hibernate. They reduce the demand of their body for
energy to an absolute minimum for long periods of time and pass
into a state of dormancy. But when the external environmental
temperature rises above a certain point some mechanism awakens
them and they become as active as any
other warm-blooded animal,
thereafter maintaining their body temperature throughout the
season of warm weather as other warm-blooded animals do throughout
There is a third class of animals,
among which man seems to be but one among many, which
have an in-built thermoregulatory system. Except under very extraordinary
circumstances and with extreme rarity, this system maintains
the body temperature as a whole within a degree or two of some
norm ‹ in mammals around 98 degrees F. and in birds a few
I have emphasized the word seems
in connection with man, because in point of fact his thermoregulatory
system is quite unique and involves several mechanisms which
are not found in other animals in spite of appearances to the
Briefly, the system works somewhat as follows: When the human
body is threatened with a fall in temperature, the first line
of defense is what is called peripheral vasoconstriction, in
which the circulating blood is prevented from flowing through
the tiny capillaries immediately at the skin surface and is short-circuited
back into the venous return flow system through special channels
(anastomoses). As a result, it does not reach the surface where
it would be chilled by radiation loss and by conduction to the
cold surface. The effect is that the skin turns white. At the
same time, this white skin acquires approximately the insulating
value of cork by the reduction of its fluid content and correspondingly
lowered conductivity. (1l4)
If this first line of defense proves
insufficient, the body initiates a second defense mechanism,
namely, the tightening up of skeletal muscles, especially in
the limbs. This muscle tension generates heat metabolically and
can actually double the resting metabolism of the body. It also,
of course, accumulates waste from the breakdown products of the
metabolism and results in the feeling of stiffness and ache that
is experienced after exposure to the cold for a sufficient length
of time. Muscle tension is maintained by the asynchronous firing
of nerve impulses to the muscles.
If this second line of defense
mechanism still proves inadequate, then the asynchronous firing
of nerve impulses is synchronized and the muscles begin to contract
in unison. We experience this as shivering. And if shivering
is allowed (one should not try to suppress
113. As Douglas J. H. K. Lee put it, "Man
is supreme as a Homeotherm." See "Heat and Cold,"
in Annual Review of Physiology. vol.10. 1948, p.368.
pg.12 of 16
114. E. F. DuBois gives the specific conductivity of epidermis,
subcutaneous fat, and muscle tissue when not bathed in sweat
water and in a condition of vasoconstriction as 0.00047 to 0.00050
gm. cal/sec./cm2/cm., compared with the specific conductivity
of cork, which is 0.0007.
it), metabolic heat
generated within the body may be increased threefold.
We therefore have a dual mechanism
for maintaining the body temperature against a fall which involves
muscular activity and a shift in circulation. Animals
shiver, but it does not appear that they have the human defense
of a closed-down peripheral circulation to reinforce its effect.
It should be understood that the circulation of the blood is
of crucial importance in the matter of temperature regulation,
acting rather like a hot or cold water system in a house, the
fluid itself forming the heat reservoir and by its circulation
providing a highly efficient heat exchanger.
When the body is threatened with
a temperature rise, a threat which incidentally is far
more dangerous to man, a somewhat different mechanism is set
in motion. The first line of defense is, again, a change in the
circulation of the blood at the periphery. In this instance,
miles of tiny capillaries are opened up and the blood floods
through them very close to the skin surface. This is known as
vasodilatation, and the visual effect is that the skin reddens.
It happens in the cheeks very rapidly under emotional stress
(i.e., blushing). Certain drugs like alcohol will also produce
the same effect of reddening in the face and neck. A rise in
body temperature due to an increase in environmental temperature
is immediately counteracted by this peripheral vasodilatation.
The mechanical effect is now to allow the blood to cool at the
surface. Deep body heat is thereby transported and eliminated
by radiation and conduction from the skin surface.
If this should prove insufficient,
a second line of defense is at once initiated, a line of defense
which, contrary to popular opinion, is believed to be unique
in man. This is technically known as thermogenic sweating. The
thermostat in the body appears to be situated in the hypothalamus
which is bathed in blood and responds to minute changes in blood
A rise of 0.01 degrees C in hypothalamic temperature is sufficient
to initiate sweating when the set point has been reached. (1l6) During sweating, the
body surface becomes bathed in a watery fluid expressed to the
skin surface via some two million sweat glands, where it evaporates.
The evaporation of water occurs only where the ambient air is
able to absorb the
115. Custance, Arthur C., "The Existence,
Nature, and Behaviour of the Set-point in the Human Thermostat,"
DREO Report 622, Defence Research Board., Ottawa, 1970, 36 pages.
116. For a fuller discussion: T. H. Benzinger, "The Human
Thermostat," in Temperature: Its Measurement and Control
in Science and Industry, vol.3, no.3, Reinhold, New York,
water vapour. When this
can be 100 percent effective, the amount of heat removed from
the body under certain circumstances can be extraordinary since
the body has the ability to sweat copiously. In our own experiments,
we have not infrequently observed that men can lose five or six
pounds (up to three liters) of body water by this means within
a single hour. This is under extreme conditions of heat stress,
but it can be sustained for a surprising length of time without
ill effect provided that the water is replaced. Very little rise
in body temperature will occur under these conditions. The moment
sweating is prevented by the use of drugs which suppress it (117) or is made valueless
because the water expressed to the skin surface cannot evaporate,
deep body temperature will begin to rise precipitously ‹
and with fatal results.
These two mechanisms of handling
heat and cold contribute fundamentally to man's ability to live
in the Arctic or in the tropics with comparative ease. On the
whole, he sustains the thermal stress better when it is negative,
i.e., when there is a threat to the reduction of his body temperature.
(1l8) He is better
in the cold than in the heat, though not always as comfortable.
Being such a creature as he is, man prefers to feel warm. But
in point of fact, he is in much greater danger from heat and
is likely to be much less energetic both physically and intellectually.
He therefore tends to over-compensate against the cold by heating
his buildings more than he really needs to do, thus reducing
his acclimatization to the cold, a circumstance which only increases
his sensitivity to it and his distaste for it. Nevertheless,
he is uniquely equipped to maintain the temperature of his vital
organs, especially his brain, at an optimum level for fruitful
and energetic employment.
His body is exceptional in this
regard. Many animals have sweat glands, some of them in the mouth
(like dogs), some of them over the whole body surface (like horses),
but in Nature no animal has the ability to prevent a temperature
rise in times of heat stress which is comparable to man's. In
spite of appearances to the contrary, the sweating of horses
is initiated for quite other reasons and serves a cooling function
only by accident and with nothing like the efficiency that it
serves in man. (1l9)
Physiologically, the sweating of
117. Custance, Arthur C., "A Method of
Measuring the Effect of Drugs on Sweating as a Function of Time,"
Canadian Medical Association Journal, vol.95, 1966, p.871-874.
pg.14 of 16
118. Custance, Arthur C., "Stress-Strain Relationship of
Man in the Heat," Medical Services Journal Canada,
vol.23, no.5, 1967, p.721-726.
119. Sweating of animals: see, for example with respect to horses,
Stephen Rothman, Physiology and Biochemistry
of the Skin, University of Chicago Press, 1955, p.166.
Also, H. M. Frankel et al., "Effects of Type of Restraint
upon Heat Tolerance in Monkeys," Proceedings of Experimental
Biology and Medicine, vol.97, 1957, p.339-341; C. H. Wyndham,
"Role of Skin and Core Temperatures in Man's Temperature
Regulation," Journal of Applied Physiology, vol.20,
1965, p.36; J. D. Hardy, "Summary Review of Heat Loss
and Heat Production in Physiological Temperature Regulation,"
NADC-MA-5413, U. S. Naval Air Development Center, Johnsville,
Pa., October 1954, p.12; and "Control of Heat Loss and Heat
Reduction in Physiological Temperature Regulation," Harvey
Lectures Series, 49, Academic Press, New York, 1953-54, pp.247-252;
Sir Charles Lovett Evans, "The Autonomic Nervous System"
British Medical Bulletin, vol.13, no.3, 1957, p.154,199.
horses is not thermogenic
at all, that is to say, it is not initiated by a rise in temperature
in the animal but is due to the increase in adrenaline in
the animal's bloodstream as a result of violent exercise. In
Nature the animal would not sweat, because it would not exercise
itself as man exercises it. In addition to this, the circulatory
adjustments of which the human body is capable in response to
temperature fluctuation is not known in any other animal. (120) Thus man has clearly
been built to maintain his body temperature against
challenges with which no other species is likely to be faced
in Nature. These circulatory adjustments involve a tremendously
complex neuromuscular activity for which the human body seems
to be expressly designed, and one can only suppose, therefore,
that God knew what would happen to man after he fell and made
provision beforehand for just such a contingency, a provision
which He did not have to make when He designed all the other
creatures which were to share his world but not share his ubiquity.
The whole body
of man has, therefore, clearly been designed to support and enhance
the uniqueness of his mind. Mind, tongue, and hand have somehow
been structured in a very remarkable way to give coordinated
expression to the sum total of human potential to the power of
reflection, of communication, and of creation; in fact; at one
and the same time, of having dominion over the rest of God's
creation and yet of worshipping the Creator. But it is not merely
the structure of his brain and the anatomy of his body which
have made these things possible. Man's uniqueness goes deeper
than this. In some not yet clearly understood way, his whole
physiological organization and the very special quality of his
spirit have together played a part in leading inevitably to the
kind of culture that he creates as a framework for his own self-expression
and restraints, and -- in the final analysis -- the kind of redemption
he needs and is capable of apprehending by faith. We next look
first at the kind of culture he has
120. Circulatory adjustment in man: see on
this, for example, R. H. Fox and O. G. Edholm in "Nervous
Control of Cutaneous Circulation," British Medical Bulletin,
vol.19, no.2, 1963, p.110-114.
created and why it has
almost inevitably taken the form it has. Then we look at his
combined need for and capacity for salvation, a truly unique
need and capacity which apparently has never applied to any other
of God's creatures, whether angel or animal.
pg.16 of 16
Copyright © 1988 Evelyn White. All rights
Previous Chapter Next
Home | Biography
| The Books | Search
| Order Books | Contact